Methodology for the Estimation of the Aerodynamic Drag Parameters of Cyclists

2019 ◽  
Author(s):  
Alejandra Polanco ◽  
Juan Fuentes ◽  
Sebastián Porras ◽  
Daniel Castiblanco ◽  
Julián Uribe ◽  
...  
Keyword(s):  
Drag Force ◽  
Aerodynamic Drag ◽  
Cycling Performance ◽  
Experimental Methodology ◽  
Frontal Area ◽  
Relevant Effect ◽  
Aerodynamic Parameters ◽  
Resistive Forces ◽  
Drag Area

Abstract The aerodynamic drag force has a relevant effect on cycling performance since it is one of the major resistive forces acting on the bicycle. For this reason, this paper presents the development of an experimental methodology to estimate the aerodynamic parameters of a bicycle-cyclist set. The methodology combines outdoor measurements to estimate the drag area with indoor measurements to measure the projected frontal area. The methodology was implemented to quantify the effect of posture in the aerodynamic parameters of a group of cyclists. The tests were performed to characterize the drag parameters associated with three postures defined by the position of the grip on the handlebar: tops, hoods, and drops. Significant differences in the aerodynamic parameters were found for the postures studied through the proposed methodology. The posture variation led to reductions of up to 11.8% in the drag area of the cyclists when passing from tops to drops posture. The results obtained are in agreement with the literature indicating that the implementation of the methodology is feasible for the estimation of the aerodynamic parameters in cycling.

Influence of Altitude on the Performance of a Bicycle-Cyclist Set

2017 ◽  
Author(s):  
Mateo Morales ◽  
Sergio D. Roa ◽  
Luis E. Muñoz ◽  
Diego A. Ferreira ◽  
Omar D. Lopez Mejia
Keyword(s):  
High Altitude ◽  
Drag Force ◽  
Power Output ◽  
Aerodynamic Drag ◽  
Integrated Approach ◽  
Cycling Performance ◽  
Air Density ◽  
Effort Tests ◽  
Different Altitudes

There is a tradeoff between power delivery and aerodynamic drag force when cyclists ride at different altitudes. The result is particular to the characteristics of the bicycle as well as the aerobic fitness of the cyclist. This work proposes a methodology based on an integrated approach to the study of the influence of altitude on power output and aerodynamic drag over a particular bicycle-cyclist set. The methodology consists of an independent analysis for each of the effects, to conclude with an integration of results that allows estimating the overall effect of altitude on cycling performance. A case study for the application of the methodology was developed, and the obtained results apply for the specific bicycle-cyclist set under analysis. First, the relationship between power and time was analyzed for a male recreational cyclist based on all-out effort tests at two different altitudes: 237 meters and 2652 meters above sea level (m.a.s.l). Second, the effects of environmental conditions on air density and drag area coefficient due to altitude changes were analyzed based on Computational Fluid Dynamics (CFD) simulations. It was found that for the bicycle-cyclist set under study, the sustainable power output for 1-hour cycling was reduced 45W for the high-altitude condition as a consequence of the reduction in the maximum oxygen uptake capacity. In addition, the aerodynamic drag force is reduced in greater proportion due to the change in air density than due to the change in drag coefficient. Finally, the results of both effects were integrated to analyze the overall influence of altitude on cycling performance. It was found that for the analyzed case study, the aerodynamic advantage at higher altitude dominates over the disadvantage of reduction in power output: despite delivering 45W less, the subject can travel an additional distance of 900 meters during a one hour ride for the high-altitude condition compared to that in low altitude.

scholarly journals Estimating Cycling Aerodynamic Performance Using Anthropometric Measures

2020 ◽  
Vol 10 (23) ◽  
pp. 8635
Author(s):  
Raman Garimella ◽  
Thomas Peeters ◽  
Eduardo Parrilla ◽  
Jordi Uriel ◽  
Seppe Sels ◽  
...  
Keyword(s):  
Drag Force ◽  
Joint Angle ◽  
Aerodynamic Drag ◽  
Linear Regression Analysis ◽  
3D Models ◽  
Frontal Area ◽  
Coefficient Of Determination ◽  
Anthropometric Measures ◽  
Aerodynamic Efficiency ◽  
Angle Data

Aerodynamic drag force and projected frontal area (A) are commonly used indicators of aerodynamic cycling efficiency. This study investigated the accuracy of estimating these quantities using easy-to-acquire anthropometric and pose measures. In the first part, computational fluid dynamics (CFD) drag force calculations and A (m2) values from photogrammetry methods were compared using predicted 3D cycling models for 10 male amateur cyclists. The shape of the 3D models was predicted using anthropometric measures. Subsequently, the models were reposed from a standing to a cycling pose using joint angle data from an optical motion capture (mocap) system. In the second part, a linear regression analysis was performed to predict A using 26 anthropometric measures combined with joint angle data from two sources (optical and inertial mocap, separately). Drag calculations were strongly correlated with benchmark projected frontal area (coefficient of determination R2 = 0.72). A can accurately be predicted using anthropometric data and joint angles from optical mocap (root mean square error (RMSE) = 0.037 m2) or inertial mocap (RMSE = 0.032 m2). This study showed that aerodynamic efficiency can be predicted using anthropometric and joint angle data from commercially available, inexpensive posture tracking methods. The practical relevance for cyclists is to quantify and train posture during cycling for improving aerodynamic efficiency and hence performance.

Parametric Study of Drag Force on a Formula Student Electric Race Car Using CFD

2014 ◽  
Vol 575 ◽  
pp. 300-305 ◽  
Author(s):  
Lalit Patidar ◽  
Sri Ramya Bhamidipati
Keyword(s):  
Drag Force ◽  
Fuel Economy ◽  
Aerodynamic Drag ◽  
Pressure Coefficient ◽  
Substantial Reduction ◽  
Frontal Area ◽  
Test Case ◽  
Electric Cars ◽  
Race Car ◽  
Set Up

Aerodynamic drag plays an important role in fuel economy of the vehicle especially for electric cars directly affecting the range. The objective of Aerodynamics subsystem of IIT Bombay racing team is to predict and minimize drag force on the Formula student electric race car thereby improving the performance. A standard generic car body known as Ahmed body is taken to set up simulation parameters in FLUENT by validating a test case against the experimental data available in literature. Variation and dependence of drag force on parameters such as frontal area, distribution of pressure coefficient and pressure loss in wake region is studied numerically. Comparison is made between Formula Student 2013 car Evo2 and newly designed car Evo3 for coming season of Formula Student 2014. A substantial reduction in drag force of 18.8% is achieved which can be attributed to lower frontal area and streamlined bodyworks design. Energy consumption of the vehicle for endurance race is reduced by 11.5 % improving the fuel economy.

Aerodynamics of Cyclist Posture, Bicycle and Helmet Characteristics in Time Trial Stage

2012 ◽  
Vol 28 (3) ◽  
pp. 317-323 ◽  
Author(s):  
Vincent Chabroux ◽  
Caroline Barelle ◽  
Daniel Favier
Keyword(s):  
Statistical Analysis ◽  
Wind Tunnel ◽  
Drag Coefficient ◽  
Drag Force ◽  
Time Trial ◽  
Frontal Area ◽  
Significant Gain ◽  
Upper Limbs ◽  
Force Coefficient ◽  
Coefficient Reduction

The present work is focused on the aerodynamic study of different parameters, including both the posture of a cyclist’s upper limbs and the saddle position, in time trial (TT) stages. The aerodynamic influence of a TT helmet large visor is also quantified as a function of the helmet inclination. Experiments conducted in a wind tunnel on nine professional cyclists provided drag force and frontal area measurements to determine the drag force coefficient. Data statistical analysis clearly shows that the hands positioning on shifters and the elbows joined together are significantly reducing the cyclist drag force. Concerning the saddle position, the drag force is shown to be significantly increased (about 3%) when the saddle is raised. The usual helmet inclination appears to be the inclination value minimizing the drag force. Moreover, the addition of a large visor on the helmet is shown to provide a drag coefficient reduction as a function of the helmet inclination. Present results indicate that variations in the TT cyclist posture, the saddle position and the helmet visor can produce a significant gain in time (up to 2.2%) during stages.

scholarly journals Aerodynamic Performance of Road Vehicles

2020 ◽  
Vol 9 (6) ◽  
pp. 642-645
Keyword(s):  
Wind Tunnel ◽  
Drag Force ◽  
Aerodynamic Drag ◽  
Aerodynamic Performance ◽  
Polished Surface ◽  
Anova Analysis ◽  
Road Vehicles ◽  
Car Model ◽  
Group Data ◽  
Scale Models

Aerodynamic drag has been experimentally estimated for scale models of a passenger car and a commercial truck in a wind tunnel. Polished surface has resulted up to 15 % reduction in drag force and add-on has resulted in 57% increase in drag force of a car model whereas 2.6 % reduction in drag force has resulted by using deflector in a commercial truck model. Anova analysis shows variation in mean of group data.

A Novel Training Bike and Camera System to Evaluate Pose of Cyclists

2020 ◽  
Author(s):  
Raman Garimella ◽  
Koen Beyers ◽  
Thomas Peeters ◽  
Stijn Verwulgen ◽  
Seppe Sels ◽  
...  
Keyword(s):  
Inertial Sensors ◽  
Sagittal Plane ◽  
Aerodynamic Drag ◽  
Linear Regression Analysis ◽  
The Body ◽  
Frontal Area ◽  
Motion Sensors ◽  
Joint Angles ◽  
Camera System ◽  
Flexion Extension

Abstract Aerodynamic drag force can account for up to 90% of the opposing force experienced by a cyclist. Therefore, aerodynamic testing and efficiency is a priority in cycling. An inexpensive method to optimize performance is required. In this study, we evaluate a novel indoor setup as a tool for aerodynamic pose training. The setup consists of a bike, indoor home trainer, camera, and wearable inertial motion sensors. A camera calculates frontal area of the cyclist and the trainer varies resistance to the cyclist by using this as an input. To guide a cyclist to assume an optimal pose, joint angles of the body are an objective metric. To track joint angles, two methods were evaluated: optical (RGB camera for the two-dimensional angles in sagittal plane of 6 joints), and inertial sensors (wearable sensors for three-dimensional angles of 13 joints). One (1) male amateur cyclist was instructed to recreate certain static and dynamic poses on the bike. The inertial sensors provide excellent results (absolute error = 0.28°) for knee joint. Based on linear regression analysis, frontal area can be best predicted (correlation > 0.4) by chest anterior/posterior tilt, pelvis left/right rotation, neck flexion/extension, chest left/right rotation, and chest left/right lateral tilt (p < 0.01).

The influence of the thermal wake due to pulsating optical discharge on the aerodynamic-drag force

2018 ◽  
Vol 25 (2) ◽  
pp. 257-264 ◽  
Author(s):  
T. A. Kiseleva ◽  
A. A. Golyshev ◽  
V. I. Yakovlev ◽  
A. M. Orishich
Keyword(s):  
Drag Force ◽  
Aerodynamic Drag ◽  
Optical Discharge ◽  
Thermal Wake

scholarly journals Interaction between an aerodynamically driven, wall-bound drop and a single groove

2020 ◽  
Vol 229 (10) ◽  
pp. 1757-1769 ◽  
Author(s):  
Patrick M. Seiler ◽  
Ilia V. Roisman ◽  
Cameron Tropea
Keyword(s):  
Channel Flow ◽  
Drag Force ◽  
High Speed ◽  
Adhesion Force ◽  
Aerodynamic Drag ◽  
Rear Side ◽  
Threshold Condition ◽  
High Speed Video ◽  
Gravity Forces ◽  
Typical Time

Abstract The interaction between an air-driven, wall-bound drop and a groove in the wall of a channel flow has been investigated experimentally using a high-speed video system. Three major outcomes of drop interaction with the groove are observed: (i) the drop passes over the groove, (ii) the drop is immediately fully captured in the groove or (iii) the drop is captured after first wetting the rear side of the groove. The mechanisms leading to these different outcomes are governed by the aerodynamic drag force, by inertial and gravity forces, and by the adhesion force associated with the substrate wettability. A threshold condition for drop capture is developed, based on the ratio of the typical time for drop passage over the groove to the time for the drop to be sucked into the groove. It has been shown that the probability for drop capture increases for higher Bond numbers.

scholarly journals Numerical Study of the Generic Sports Utility Vehicle Design with a Drag Reduction Add-On Device

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Shubham Singh ◽  
M. Zunaid ◽  
Naushad Ahmad Ansari ◽  
Shikha Bahirani ◽  
Sumit Dhall ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Numerical Study ◽  
Fuel Efficiency ◽  
Ansys Fluent ◽  
Mean Pressure ◽  
Aerodynamic Drag Coefficient ◽  
Total Base ◽  
Aerodynamic Parameters

CFD simulations using ANSYS FLUENT 6.3.26 have been performed on a generic SUV design and the settings are validated using the experimental results investigated by Khalighi. Moreover, an add-on inspired by the concept presented by Englar at GTRI for drag reduction has been designed and added to the generic SUV design. CFD results of add-on model and the basic SUV model have been compared for a number of aerodynamic parameters. Also drag coefficient, drag force, mean surface pressure, mean velocities, and Cp values at different locations in the wake have been compared for both models. The main objective of the study is to present a new add-on device which may be used on SUVs for increasing the fuel efficiency of the vehicle. Mean pressure results show an increase in the total base pressure on the SUV after using the device. An overall reduction of 8% in the aerodynamic drag coefficient on the add-on SUV has been investigated analytically in this study.

scholarly journals Physical and Aerodynamic Properties of Lavender in relation to Harvest Mechanisation

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Christos I. Dimitriadis ◽  
James L. Brighton ◽  
Mike J. O’Dogherty ◽  
Maria I. Kokkora ◽  
Anastasios I. Darras
Keyword(s):  
Surface Area ◽  
Drag Force ◽  
Aerodynamic Drag ◽  
Reynolds Numbers ◽  
Ultimate Tensile Stress ◽  
Flower Head ◽  
Drag Forces ◽  
Aerodynamic Properties ◽  
The Mean ◽  
Harvest Moisture

A laboratory study evaluated the physical and aerodynamic properties of lavender cultivars in relation to the design of an improved lavender harvester that allows removal of flowers from the stem using the stripping method. The identification of the flower head adhesion, stem breakage, and aerodynamic drag forces were conducted using an Instron 1122 instrument. Measurements on five lavender cultivars at harvest moisture content showed that the overall mean flower detachment force from the stem was 11.2 N, the mean stem tensile strength was 36.7 N, and the calculated mean ultimate tensile stress of the stem was 17.3 MPa. The aerodynamic measurements showed that the drag force is related with the flower surface area. Increasing the surface area of the flower head by 93% of the “Hidcote” cultivar produced an increase in drag force of between 24.8% and 50.6% for airflow rates of 24 and 65 m s−1, respectively. The terminal velocities of the flower heads of the cultivar ranged between 4.5 and 5.9 m s−1, which results in a mean drag coefficient of 0.44. The values of drag coefficients were compatible with well-established values for the appropriate Reynolds numbers.

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